As illustrated by FIGS. 1A, 1B and 1C, a common prior art LED mounting arrangement results in a substantial portion of the light output going in a direction parallel to a normal to the top surface of a semiconductor photonic chip 12 as seen in FIG. 1B. As seen in FIG. 1A, a top view of an LED 10, the semiconductor photonic chip 12 is mounted on a substrate 14 which is in turn mounted on a bonding pad 16. The chip 12 is encapsulated beneath an optical lens 18 which focuses the light emitted by the chip 12.
FIG. 1B shows a side view of LED 10 with a plurality of light rays relative to a normal, N, to the top surface of chip 12 illustrating the light emitted by chip 12 as it passes out of lens 18.
FIG. 1C shows an illustrative plot of the light emitted by LED 10 with the y-axis representing the intensity, I, and the x-axis representing the angle, θ, of the emitted light with respect to the normal, N, of FIG. 1B. As illustrated in FIG. 1C, a substantial portion of the light emitted from the LED is along or near the normal, N. Conversely, only a small percentage is emitted sideways. For further details of exemplary prior art LED packages with the bulk of the light intensity emitted near the normal, N, see, for example, the product literature for the XLamp™ 7090 from Cree, Incorporated, as well as that for the LumiBright Light Engine from Innovations in Optics, Inc. The Light Engine product employs a reflective cup which is asserted to direct three times more light into a useable cone angle.
While in some applications it will be recognized that such an emission pattern is advantageous, it will be recognized, however, that for other applications, as discussed further below, it will be desirable to change the light emission pattern. It will further be recognized that good thermal heat dissipation, and ease of manufacture with a small number of parts are also highly desirable.